Periodontal disease is a major cause of tooth loss in adults over thirty-five years of age. It is caused by bacteria found in plague which is a film that constantly forms on teeth. The bacteria produce toxins which irritate the gums eventually destroying the attachment of the gums to the teeth. Infections to the bone develop beneath the gums and the gingival sulcus deepens to form a periodontal pocket.
Periodontal disease can be treated successfully if detected at an early stage. At the early stage, often called gingivitis, only the gum tissue is affected and if the condition is not kept under control it can lead to a more advanced condition called periodontitis. Periodontitis can affect the gums, bone and the supporting structures surrounding the teeth.
Some presently available means for treating periodontal disease in a non specific manner include long acting capsules or tablets held in the mouth, buccal implants for releasing drugs into the saliva, topically applied gels, and topically applied drug containing bandages. Other means used to treat periodontal disease in a more site-specific manner include impregnated or drug releasing forms of dental floss and solid absorbable fibers of polyglycolic acid with therapeutic agents incorporated therein.
Superficial drug delivery to the periodontal pocket can be ineffective for several reasons. During periodontal disease, gum tissue within the pocket becomes inflamed and surrounds the necks of the teeth. The inflamed areas surrounding the teeth can prevent diffusion of the therapeutic agent to the infected area if the agent is applied superficially. Further, crevicular fluid (similar compositionally to plasma) continuously is produced by the lining of the periodontal pocket when a subject has a periodontal disease. The production of crevicular fluid causes an outward flow away from the lining of the pocket making it difficult to apply therapeutic agents to the periodontal pocket in a manner allowing diffusion of the agents through the crevicular fluid to the desired site.
An interpocket drug delivery device is described in U.S. Pat. No. 4,764,377 issued to Goodson on Aug. 16, 1988. Goodson describes the use of a polymeric matrix, such as ethylene vinyl acetate co-polymer, as a packing containing a therapeutic agent. The therapeutic agent diffuses out of the polymeric packing providing continuous therapy for the treatment site. The packing of Goodson is not placed in the periodontal pocket in a solution or paste form.